The present invention relates to coopering and involves method and apparatus used in the process of manufacturing wooden staves. In particular, the present invention relates to an apparatus for mitring the edged profiles of elongate wooden pieces or blanks based on their width and shape to form wine and/or spirit barrel staves.
It is to be understood that although the present invention relates specifically to wooden staves used in the construction of barrels, it could equally well be applied to the dimensioning of plastic or even metal staves using the same principles.
In the process of manufacturing staves for use in the construction of wooden barrels, tubs, planters, and other containers of similar shape, hardwood trees such as oak are first cut into billets or tree sections of random lengths and widths. Typically, the size and shape of the sections depend upon the size of the wooden barrels for which the staves are being manufactured. These irregular wooden pieces are typically quarter sawn, cut into wedged or substantially pie shaped cross sections which are then cut to form rough or unfinished barrel staves.
The opposing side edges of the partially formed staves must be further processed by mitring the edged profiles for the purpose of forming joints with like surfaces of other staves forming a barrel. There are various known methods of mitering the edges of an unfinished stave.
For example, one such method is to mitre the edges by passing the stave through a power driven cutter to mitre a first edge and then positioning the stave on a second power driven cutter to mitre the opposite longitudinal side. The mitering operation is accomplished by visually or mechanically aligning the stave with the plane of the respective mitering cutter, and many times results in forming a stave with its side surfaces converging toward one end. This is undesirable and the stave must be rejected. Furthermore, such apparatus requires multiple personnel to operate.
More recent mitering techniques have involved the use of semi-automated equipment whereby an unfinished stave is made to travel along a track and is exposed to a pair of motor driven cutters which are arranged on either side of the track. Some of these apparatus include means to adjust the spacing between the cutters in response to a measured dimension of the unfinished stave. However, there are a number of problems associated with such equipment.
Firstly, prior art equipment which adjusts the spaced apart distance between cutters based on a dimension of the unfinished stave, is only suitable for producing staves having straight longitudinal sides. This is because the saws do not move during the cutting process, they are simply locked in the position governed by the measured dimension. This is not suitable for barrels such as wine or spirit barrels which require accurate profiled longitudinal sides.
Secondly, barrel forming staves often arrive at such workstations having variable widths along the length of the staves. Therefore, where the cut is based on only the leading or trailing edge width for example, this may result in an inaccurate cut because the width at the leading or trailing edge may be greater than the width at other points along the stave length. In other words, if the distance between saws is based solely on the leading edge width, there will be points along the stave where there is no material to be cut and will result in an uneven edge.
Most importantly though where an arcuate cut is required, that is, where the edge angle and profile is a function of barrel diameter, the width of the unfinished stave needs to be determined along its entire length to ensure that a maximum amount of material is used and that a minimum amount of material is wasted. No equipment known to the applicant is capable of producing such staves.
It is therefore an object of the present invention to overcome the aforementioned problems or to provide the public with a useful alternative.